Sarnat J A, Koutrakis P, Suh H H
Harvard School of Public Health, Department of Environmental Health, Boston, Massachussetts, USA.
J Air Waste Manag Assoc. 2000 Jul;50(7):1184-98. doi: 10.1080/10473289.2000.10464165.
We conducted a multi-pollutant exposure study in Baltimore, MD, in which 15 non-smoking older adult subjects (> 64 years old) wore a multi-pollutant sampler for 12 days during the summer of 1998 and the winter of 1999. The sampler measured simultaneous 24-hr integrated personal exposures to PM2.5, PM10, SO4(2-), O3, NO2, SO2, and exhaust-related VOCs. Results of this study showed that longitudinal associations between ambient PM2.5 concentrations and corresponding personal exposures tended to be high in the summer (median Spearman's r = 0.74) and low in the winter (median Spearman's r = 0.25). Indoor ventilation was an important determinant of personal PM2.5 exposures and resulting personal-ambient associations. Associations between personal PM2.5 exposures and corresponding ambient concentrations were strongest for well-ventilated indoor environments and decreased with ventilation. This decrease was attributed to the increasing influence of indoor PM2.5 sources. Evidence for this was provided by SO4(2-) measurements, which can be thought of as a tracer for ambient PM2.5. For SO4(2-), personal-ambient associations were strong even in poorly ventilated indoor environments, suggesting that personal exposures to PM2.5 of ambient origin are strongly associated with corresponding ambient concentrations. The results also indicated that the contribution of indoor PM2.5 sources to personal PM2.5 exposures was lowest when individuals spent the majority of their time in well-ventilated indoor environments. Results also indicate that the potential for confounding by PM2.5 co-pollutants is limited, despite significant correlations among ambient pollutant concentrations. In contrast to ambient concentrations, PM2.5 exposures were not significantly correlated with personal exposures to PM2.5-10, PM2.5 of non-ambient origin, O3, NO2, and SO2. Since a confounder must be associated with the exposure of interest, these results provide evidence that the effects observed in the PM2.5 epidemiologic studies are unlikely to be due to confounding by the PM2.5 co-pollutants measured in this study.
我们在马里兰州巴尔的摩市开展了一项多污染物暴露研究，1998年夏季和1999年冬季期间，15名不吸烟的老年受试者（年龄>64岁）佩戴多污染物采样器12天。该采样器可同时测量24小时内个人对PM2.5、PM10、SO4(2-)、O3、NO2、SO2以及与尾气相关的挥发性有机化合物的综合暴露量。本研究结果表明，夏季环境PM2.5浓度与相应个人暴露量之间的纵向关联往往较高（斯皮尔曼等级相关系数中位数r = 0.74），而冬季则较低（斯皮尔曼等级相关系数中位数r = 0.25）。室内通风是个人PM2.5暴露量以及由此产生的个人与环境关联的一个重要决定因素。在通风良好的室内环境中，个人PM2.5暴露量与相应环境浓度之间的关联最强，且随着通风情况而降低。这种降低归因于室内PM2.5来源的影响日益增加。SO4(2-)测量结果为此提供了证据，SO4(2-)可被视为环境PM2.5的一种示踪剂。对于SO4(2-)，即使在通风不良的室内环境中，个人与环境的关联也很强，这表明个人对源自环境的PM2.5的暴露与相应环境浓度密切相关。结果还表明，当个体大部分时间处于通风良好的室内环境时，室内PM2.5来源对个人PM2.5暴露量的贡献最低。结果还表明，尽管环境污染物浓度之间存在显著相关性，但PM2.5共污染物造成混杂的可能性有限。与环境浓度不同，PM2.5暴露量与个人对PM2.5 - 10、非环境来源的PM2.5、O3、NO2和SO2的暴露量没有显著相关性。由于混杂因素必须与感兴趣的暴露相关联，这些结果提供了证据，表明在PM2.5流行病学研究中观察到的效应不太可能是由本研究中测量的PM2.5共污染物造成的混杂所致。
